Selective CMP of in-situ deposited multilayer films to enhance nonplanar step height reduction

Abstract

A structure and method for chemical-mechanical polishing of a semiconductor body (100) having topographical steps (102) on a surface thereof. A first film (104) having a first CMP removal rate is deposited over the surface of a semiconductor body (100). A second film (106) having a second CMP removal rate is deposited over the first film (104). The second removal rate is not equal to the first removal rate. CMP is performed on the semiconductor body (100) such that the first film (104) is initially exposed only over the topographical steps (102). CMP continues until the semiconductor body (100) has a planarized surface. Because one of the films (104, 106) has a high removal rate and the other (106,104) has a low removal rate, a CMP process is provided requiring less time and having better process uniformity and process latitude.

What is claimed is: 
     
       1. A method for chemical-mechanical polishing of a semiconductor body having topographical steps on a surface thereof, comprising the steps of: depositing a first film having a first removal rate over the surface of said semiconductor body;   depositing a second film having a second removal rate over said first film, wherein said second removal rate is not equal to said first removal rate; depositing a third film having a third removal rate over said second film, wherein said third removal rate is not equal to said second removal rate;     chemically-mechanically polishing said semiconductor body such that initially said second film is exposed only over said topographical steps and then after further polishing said first film is initially exposed only over said topographical steps, and   continuing said chemically-mechanically polishing step until said semiconductor body has a planarized surface.   
     
     
       2. The method of claim 1, wherein said first removal rate is greater than said second removal rate. 
     
     
       3. The method of claim 2, wherein said first film comprises a material having a more positive tensile stress than said second film. 
     
     
       4. The method of claim 2, wherein said first film comprises a material having a higher dopant concentration that said second film. 
     
     
       5. The method of claim 1, wherein said second removal rate is greater than said first removal rate. 
     
     
       6. The method of claim 5, wherein said second film comprises a material having a more positive tensile stress than said first film. 
     
     
       7. The method of claim 5, wherein said second film comprises a material having a higher dopant concentration that said first film. 
     
     
       8. The method of claim 1, wherein said third removal rate and said first removal rate are less than said second removal rate. 
     
     
       9. A method for planarizing the surface of a semiconductor body having topographical steps and field areas located thereon, comprising the step of: forming a multi-layer interlevel dielectric over the surface of said semiconductor body comprising the steps of forming a first layer having a first removal rate, forming a second layer having a second removal rate different from said first removal rate and forming a third layer having a third removal rate over the second layer; and   chemically-mechanically polishing said multi-layer interlevel dielectric to planarize the surface of the semiconductor body, wherein the second layer is initially exposed over the topographical steps while the third layer remains over the field areas such that polishing increases over the topographical steps and then subsequently, as polishing continues, the first layer is exposed over the topograghical steps while the second layer remains over the field areas such that polishing decreases over the topographical steps.   
     
     
       10. The method of claim 9, wherein said first removal rate is greater than said second removal rate and wherein said chemical-mechanical polishing step exposes said first layer over said topographical step while said second layer remains over the field areas such that polishing increases over said topographical steps when said first layer is exposed. 
     
     
       11. The method of claim 10, wherein said chemical-mechanical polishing steps creates a planarized surface having said second layer over said field areas and said first layer over said topographical steps. 
     
     
       12. The method of claim 9, wherein said second removal rate is greater than said first removal rate and wherein said chemical-mechanical polishing step exposes said first layer over said topographical steps while said second layer remains over the field areas such that polishing slows down over said topographical steps when said first layer is exposed. 
     
     
       13. The method of claim 12, wherein said chemical-mechanical polishing steps creates a planarized surface having said first layer over said field areas and said topographical steps. 
     
     
       14. The method of claim 12, wherein said first layer is a polish stop for said chemically-mechanically polishing step.